In a process for manufacturing a semiconductor device, there has been a case that a first substrate and a second substrate are joined. For example, in a case to manufacture a semiconductor device which includes a backside illumination type imaging element, a surface of the second substrate is joined to a surface of the first substrate at which a semiconductor element such as a photodiode is formed.
Subsequently, a light-receiving face is formed by grinding a back face of the first substrate to the vicinity of the photodiode having the second substrate as a support substrate, and then, an antireflection film, a color filter, a micro lens for collecting light and the like are sequentially formed at the light-receiving face. Thus, a semiconductor device which includes a backside illumination type imaging element is manufactured.
Here, the abovementioned first substrate is apt to be formed such that a peripheral portion is to be thinner than a center portion through the process to form the semiconductor element at the surface. Accordingly, when the surface of the second substrate is joined to the surface of the first substrate, a poor joint area occurs at the peripheral portions of joint faces. Since the semiconductor element formed at the poor joint area is subjected to edge-cutting, there has been a problem that a yield rate of the first substrate is decreased as a whole.